Linear motion ball bearings

ABSTRACT

A linear motion ball bearing has an outer sleeve formed from a flat blank rolled into a circular split-sleeve, a cylindrical cage situated within the bore of the outer sleeve and defining therewith continuous ball races filled with a plurality of balls, the axial gap and bore diameter of the outer sleeve being variable to provide adjustment of the bearing.

BACKGROUND OF THE INVENTION

The present invention relates to a ball bearing for the longitudinalmounting of machine parts, consisting of an outer race sleeve made froma flat plate and rolled into a cylindrical tube having ball racesprovided in its bore and a cage disposed concentrically therein for theguidance of a plurality of continuous trains of balls distributed overthe circumference.

DESCRIPTION OF THE PRIOR ART

Ball bearings of the kind described above having a race sleeve made froma flat plate and rolled into a cylindrical tube are already known. Inone known embodiment, the outer race sleeve remains open at the seam toenable the sleeve bore diameter of the ball bearing to vary withincertain limits as disclosed in German Pat. No. 1,069,432. Also known isa method for making an outer race sleeve for a ball bearing, mounted forlongitudinal movement, in which the race sleeve is made from flatmaterial into which the ball races are embossed by compression of thematerial, and which is then rolled to form the cylindrical sleeve ortube. In this method the race sleeve can remain unattached at the seamor can be welded if desired, as disclosed in German Auslegeschrift1,675,057.

These known open constructions do not permit any precise adjustment ofthe sleeve bore diameter. If the bearing seat is not precisely made, theseam may open too wide, thereby, either (a) affecting the geometry ofthe bearing and thus resulting in an unequal load distribution, or (b)giving too much play of the shaft with respect to the bearing which thusruns noisily and imprecisely. The balls are already under high pressureeven without external loading; if the seam is not open wide enough, itwill bind the balls too tightly, increase friction and adversely affectease of rolling of these balls. These open constructions have theadditional disadvantage that after the hardening operation following therolling operation, a distortion of the outer race sleeve takes place,and the gaps or open seams interfere with installation in a bore in thecasing of a machine.

In known closed-seam designs, an additional welding operation isrequired, which on the one hand is difficult and expensive, and on theother hand can result in a change of shape and dimensions. Suchclosed-seam designs have the additional disadvantage that no adjustmentcan be made of the sleeve bore diameter and no resilient deformation ispossible.

SUMMARY OF THE INVENTION

The invention disclosed herein is addressed to the objective of creatinga ball bearing of the kind mentioned above, but where the outer racesleeve has the advantages of the simple and economical manufacture of arace sleeve from flat plate. With this invention the race sleevepreserves the desired shape after the rolling operation and during thehardening operation, and also permits a precise adjustment of the sleevebore diameter.

The advantages achieved by the invention are to be seen substantially inthe fact that the outer race sleeve has a simple interlocked seam afterit has been rolled. This permits movement within given limits, so thatthe danger of distortion during the subsequent hardening operation isavoided. The configuration of the interlocking elements furthermorepermits the adjustment of the circular sleeve housing within certainlimits. The abutting surfaces on the one hand prevent the outer racesleeve from expanding excessively upon installation and in operation,but on the other hand also prevent it from being excessivelyconstricted.

A preferred embodiment of the invention will now be described withreference to the drawings appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a linear motion ball bearing;

FIG. 2 is a longitudinal cross-sectional view taken along line A--A ofFIG. 1;

FIG. 3 is a side elevation view of the race sleeve of the ball bearingof FIGS. 1 and 2 after rolling to the cylindrical shape;

FIG. 4 is a plan view of the outer race sleeve of FIG. 3 in the flatstate; and

FIG. 5 is a fragmentary plan view of the seam area of the outer race ofFIG. 3, as seen in the direction of the arrow B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The linear motion ball bearing in accordance with FIGS. 1 and 2 includesthe outer race sleeve 1 which has within its bore 2 the ball races 3 forthe load-carrying balls 5 and ball races 4 for the non-load-carryingballs 5A, the balls being disposed as continuous trains. The cage 6inserted into the bore includes continuous grooves 7 for the guidance ofa plurality of continuous trains of balls 5, the grooves 7 beingdistributed about the circumference. Lastly, the end rings 8 aresituated on the ends of cage 6 and extend beyond the outer race sleeve1, these end rings covering the semicircular return sections of thecontinuous grooves 7 guiding the balls 5.

The outer race sleeve, which in the present embodiment has only theaxially disposed portions of the races 3 for the load-carrying and theraces 4 for the non-load-carrying balls 5, is made, as best seen in FIG.4, from a flat plate 9. In this plate 9 the races 3 for theload-carrying balls and races 4 for the non-load-carrying balls arecreated in an appropriate manner by cutting or non-cutting methods. Atone end 10, T-shaped tabs 11 projecting longitudinally are provided; atthe opposite end 12 correspondingly T-shaped cutouts 13 are provided.For greater ease of relubrication, oil holes 14 can be provided betweenthe pairs of races 3 and 4 of the individual continuous trains of balls.The plate 9 thus prepared is then by an appropriate method, rolled tothe cylindrical shape, and the tabs 11 are engaged to the correspondingcutouts 13, thus crossing the seam line.

It can be seen in FIG. 5 that the dimensions of the undercut surfaces 15of the cutouts 13 and of the undercut surfaces 16 of the tabs 11, andthe abutting edges 10 and 12 and the terminal edges 17 of the tabs 11and the back edges 18 of the cutouts 13, are so selected to form gaps19, 20 and 21 between the above-defined pairs of adjacent surfaces andedges. This will enable the outer race sleeve to flex to a certainextent, the abutting edges 10 and 12 preventing any further constrictionof the outer race sleeve 1, and the undercut surfaces 15 and 16preventing any further expansion of the outer race sleeve, this tab andcutout connection means thus establishing predetermined limits ofexpansion and constriction of said sleeve.

The invention is not restricted to the embodiment described above. Thus,modifications or changes are possible in the construction of the ballbearing. For example, the outer race sleeve 1 can extend over the entirelength of the bearing, i.e., it can envelop also the semicircular returnsections of the continuous ball races disposed at the ends of theaxially disposed sections of the races. Neither is the construction ofthe interlocking elements restricted to the illustrated form; instead ofthe T-shaped construction of the tabs and cutouts, other forms are, ofcourse, possible, such as dovetail-like shapes. These and othermodifications are possible without departing from the spirit and scopeof this invention as set forth in the claims appended hereto.

What is claimed is:
 1. In a linear motion ball bearing including anouter race sleeve formed from a flat plate having opposite ends, theplate bent to form a cylindrical split-sleeve tube having length in theaxial direction and defining a bore, with said opposite ends beingadjacent and circumferentially spaced thereby defining a gap thatextends generally lengthwise and circumferentially, a cage disposed insaid bore and defining therewith continuous ball raceways distributedcircumferentially with a plurality of balls disposed in said raceways,the improvement comprising connection means interconnecting one of saidadjacent ends with the other of said ends for permitting limitedrelative movement of these ends and correspondingly limited variation ofsaid gap in the circumferential direction, and correspondingly limitedvariation of the bore diameter of said outer race sleeve.
 2. A ballbearing according to claim 1 wherein said connection means comprises atleast one projection extending generally circumferentially from one ofsaid adjacent ends to and lockingly engaging the other of said ends. 3.A ball bearing according to claim 2 wherein said projection has apredetermined shape, and said connection means further comprises acutout having shape corresponding to said projection shape, saidprojection being situated in said cutout for locking engagementtherewith.
 4. A ball bearing according to claim 2 wherein saidprojection has at least one generally T-shape configuration with thestem of the T extending circumferentially from one of said ends and thecross of the T being spaced from said end, and said connection meansfurther comprises at least one cutout having a corresponding T-shape inwhich said projection is situated, said projection end cutout beingrelatively dimensioned for permitting said limited increase and decreaseof said gap in the circumferential direction.
 5. A ball bearingaccording to claim 2 wherein said connection means comprises a pluralityof projections and corresponding cutouts spaced apart in the axialdirection.
 6. A ball bearing according to claim 1 wherein the portionsof said raceways defined by said bore of said outer race sleeve aremachined surfaces.
 7. In a linear motion ball bearing including an outerrace sleeve comprising a cylindrical wall formed as a split-sleeve tubehaving length in the axial direction and defining a bore, said wall alsoincluding therein a gap extending generally lengthwise and defined byadjacent and circumferentially-shaped edges of said wall, a cagedisposed in said bore and defining therewith continuous ball racewaysdistributed circumferentially with a plurality of balls disposed in saidraceways, the improvement comprising connection means interconnectingone of said adjacent edges with the other of said edges for permittingrelative movement of these edges and correspondingly limited variationof said gap in the circumferential direction, and correspondinglylimited variation of the bore diameter of said outer race sleeve.
 8. Ina method of making an outer race sleeve for a linear motion ballbearing, the improvement comprising the steps of forming a flat platehaving opposite ends, rolling said plate into a split-sleeve cylindricalshape with said ends being positioned adjacently and circumferentiallyspaced, and interconnecting said ends in locking engagement whichpermits limited relative movement therebetween in said circumferentialdirection.
 9. A method according to claim 8 comprising the further stepsof forming on one of said ends while said plate is in a flat condition aprojection of predetermined shape and extending in the direction of saidend, forming in said other end a cutout having shape corresponding tothat of said projection, and lockingly disposing said projection in saidcutout when said plate is rolled into said split-sleeve cylindricalshape.
 10. An outer race for a rolling bearing, comprising a flat platehaving opposite ends, said plate being curved to form a split sleeve,the inside of said plate including a plurality of raceways formeddirectly on said plate to accommodate rolling elements, said oppositeends having respective mating linking means adapted to be linkedtogether to complete said sleeve, said linking means comprising amechanical interconnection having a limited circumferential play.
 11. Alinear motion ball bearing including an outer race sleeve, comprising aflat plate having opposite ends, the plate bent to form a cylindricalsplit-sleeve tube having length in the axial direction and defining abore, with said opposite ends being adjacent and circumferentiallyspaced from one another and respectively provided with complementaryinterlocking means extending generally lengthwise and circumferentiallyfrom said plate ends, said plate defining thereon continuous ballraceways distributed circumferentially for accommodating a plurality ofballs disposed in said raceways, said complementary interlocking meansnestable within one another and interconnecting one of said adjacentends with the other of said ends, wherein said interlocking means allowsmovement of one of said ends, relative to the other, therebyestablishing limits of expansion and constriction of said sleeve.